Thin films (250 nm - 1200 nm) of cubic Y3Fe5O12 (YIG) were deposited on fused silica and monocrystal Y3Al5O12 (YAG) 100 substrates by spray pyrolysis (using ethylene glycol solutions of Y-Fe(III)-citric complexes) and additionally annealed at 950 degrees Celsius in static air for 2 h. The films were afterwards irradiated by a free-running Nd-YAG laser (pulse energy 650 mJ, pulse duration 700 microseconds, energy density 100 mJ/cm2) whose onset was synchronized with that of a magnetic field pulse of nearly-square shape (magnetic induction 0.5 T, pulse duration 900 microsecond). The samples were placed normally to the direction of the magnetic field. The temperature reached at the film surface was estimated to be as high as the melting point, considerably higher than the Curie temperature. The laser-magnetic field treatment causes: a sharp weakening of the YIG/YAG films texturation, highly textured before that treatment; an increase of the crystallites size; change in the phase composition of the YIG/silica films; an increase of the magnetization by more than 45%; an increase (in the case of YIG/silica) and decrease (in the case of YIG/YAG) of the coercive force.